Nvestigation On Epidemiology And Pathogenicity Of Acinetobacter Baumannii

1. backgroundAcinetobacter baumannii is widely distributed in water, soil, the hospital surroundings and skin of human body.and it has become the main pathogens in nosocomial infection.Especially in the patients who is immunocompromised,or with tracheotomy and mechanical ventilation.In recent years, non-fermenting bacteria has in an increasing trend in clinical isolated pathogens,the most of pathogens is Acinetobacter and Pseudomonas aeruginosa, acinetobacter baumannii is the most common of Acinetobacter.Currently,acinetobacter baumannii is one of most important clinical isolated pathogens,such as Escherichia coli, Pseudomonas aeruginosa,and Staphylococcus aureus.Multi-drug resistant acinetobacter baumannii has been increasing as the widespread use of antibiotic.Carbapenem resistant Acinetobacter baumannii has gradually increased,mechaisms of carbapenem resistance include:production of carbapenemase.loss of outer membrane porin,and efflux system.Acinetobacter baumannii epidemic in a hospital easily.anti-infection treatment is difficult in clinical,so,how to control and treat infections caused by Acinetobacter baumannii has become the focus of clinical attention. In clinical,we also observed that some patients'respiratory specimens has isolated Acinetobacter baumannii,but relatively stable patients with respiratory conditions.has not obvious symptoms of pulmonary infection. We carried out this study to demonstrate the epidemiology and pathogenicity of these cases,23cases,its respiratory secretion samples has the growth of Acinetobacter baumannii from the zhejiang Provincial People's Hospital,investigation on epidemiology and pathogenicity of Acinetobacter baumannii.2. Materials and methods23strains of Acinetobacter baumannii collected from internsive care uint(ICU) in the zhejiang Provincial People's Hospital,November2010-February2011,all strains was isolated from Respiratory secretions.K-B disk diffusion method using determination of antimicrobial susceptibility test sensitivity rate. Homology of23strains of acinetobacter baumannii was analyzed by pulsed-field gel electrophoresis(PFGE).Using clinical pulmonary infection score (CPIS) evaluate the pathogenicity of Acinetobacter baumannii situation.3. Results(1) Antibiotic susceptibility rate results:21of23strains were multi-deug resistant and also highly resistant to imipenem and meropenem.The most active agents these strains were amikacin with susceptibility rate of65.22%, followed by52.17%to minocycline,gentamicin is21.73%,susceptibility rate with piperacillin,piperacillin/tazobactam, sulbactam/ampicillin, imipenem and meropenem is8.69%,susceptibility rate with Cefepime, ciprofloxacin, ceftazidime is13.04%.(2) Homology of23strains showed that23strains were classified into mainly A, B two types on PFGE pattern,10strains were type A,in which5strains were subtype A1,2 strains subtype A2, A3, A4, A5, A6were each one.Three strains isolated from hematlolgy department belongs to Type B.other Types, respectively C, D, E, F, G, H, I, J, K each one.(3) CPIS in14patients has not change,in6patients has increased,after Acinetobacter baumannii isolated from respiratory secretions.CPIS in3patients was zero,this shows that these patients has not isolated pathogens from their respiratory secretions before acinetobacter baumannii isolated from respiratory secretions.4. Conclusion(1)23strains Acinetobacter baumannii highly resistant to carbapenems(2) There are some changes of epidemic strains at different times(3) Although Acinetobacter baumannii isolated from respiratory secretions, some pathogens has not caused severe pneumonia.